In English, possessive words or phrases exist for nouns and most pronouns, as well as some noun phrases. These can play the roles of determiners (also called possessive adjectives when corresponding to a pronoun) or of nouns.
For nouns, noun phrases, and some pronouns, the possessive is generally formed with the suffix -s, but in some cases just with the addition of an apostrophe to an existing s. This form is sometimes called the Saxon genitive, reflecting the suffix's derivation from Old English. Personal pronouns, however, have irregular possessives, and most of them have different forms for possessive determiners and possessive pronouns, such as my and mine or your and yours.
Possessives are one of the means by which genitive constructions are formed in modern English, the other principal one being the use of the preposition of. It is sometimes stated that the possessives represent a grammatical case, called the genitive or possessive case, though some linguists do not accept this view, regarding the s ending, variously, as a phrasal affix, an edge affix, or a clitic, rather than as a case ending.
The possessive form of an English noun, or more generally a noun phrase, is made by suffixing a morpheme which is represented orthographically as s (the letter s preceded by an apostrophe), and is pronounced in the same way as the regular English plural ending (e)s: namely as ᵻz when following a sibilant sound (/s/, /z/, /ʃ/, /ʒ/, /tʃ/ or /dʒ/), as /s/ when following any other voiceless consonant (/p/, /t/, /k/, /f/ or /θ/), and as /z/ otherwise. For example:
Mitch /mɪtʃ/ has the possessive Mitch's ˈmɪtʃᵻz
luck /lʌk/ has the possessive luck's /lʌks/
man /mæn/ has the singular possessive man's /mænz/ and the plural possessive men's
Note the distinction from the plural in nouns whose plural is irregular: man's vs. men, wife's vs. wives, etc.
In the case of plural nouns ending in -s, the possessive is spelled by only adding an apostrophe and is pronounced the same (for example: Peasants' Revolt).